In a new study, staff claimed they were being put under more pressure to manipulate test scores, re-write pupils’ homework and help them complete coursework projects.

Figures show that more than a third of teachers admitted using tactics that could undermine their “integrity”.

Many teachers said they were increasingly required to drop parts of the curriculum to concentrate on exam practice, stage after-school coaching sessions and offer rewards in an attempt to bribe pupils into getting better results.

The study – by the Association of Teachers and Lecturers – also found that more than a quarter of teachers had been required to attend seminars run by examination boards to get vital tips on passing GCSEs and A-levels. One told how examiners hosting one event “strongly hinted which topics would come up” in the test.

The disclosure comes after an investigation by the Telegraph found evidence of examiners advising teachers at £230-a-day sessions about the exact wording that pupils should use and which questions they could expect.

Teachers' leaders claimed the findings underlined the extent to which pupils' education was being undermined by the target culture in schools.

Speaking as the ATL’s annual conference started in Manchester today, Mary Bousted, the union’s general secretary, said: “With the Government’s persistent focus on tests, exams results and league tables, many teachers and lecturers feel under enormous pressure, often at the detriment to high quality teaching, learning and development of their pupils.

“Results now appear to be more important than learning, and this does nothing to help children progress.”

The ATL surveyed more than 500 teachers across the UK as part of the study.

Three-quarters said they felt “under a lot of pressure” at school to prepare pupils for tests and exams. Seven-in-10 claimed the demands placed on staff had increased in the last two years.

It emerged that 35 per cent felt the pressure had reached such a point that it “could compromise their integrity”.

One infant school teacher – teaching children aged just seven or under – said she had been “forced to manipulate results” to avoid triggering an Ofsted inspection.

A secondary teacher told researchers her school “pushes the boundaries of exam integrity”, suggesting it helped pupils improve their coursework.

“Controlled assessments and aspects of coursework are problem areas for cheating, with senior leadership driving the agenda,” the teacher said.

One grammar school teacher added: “In some cases I end up virtually re-writing my students’ homework to match the marking criteria, rather than teach them my subject, French. There is simply not time to do both.”

Some 70 per cent of teachers increasingly turned to practice papers to improve pupils’ exam performance and a quarter gave rewards to pupils who gained the best results.

One teacher said pupils were “close to breakdown” because of the number of after-school and holiday classes staged to improve scores, adding: “Unrealistic, computer generated targets are in many cases impossible to achieve.”

In a further disclosure, almost nine-in-10 teachers admitted that the pressure to improve test scores prevented the “teaching of a broad and balanced curriculum”.

A former sixth form tutor at a Newcastle secondary school said: “When you can't get through all the curriculum, it's very tempting to teach to the exam only and miss out the rest.”

A teacher at another state secondary added: “Teaching to the test means that I am not prioritising the needs of the pupils in learning about my subject; it only prepares them to respond to formulaic questions.”